Light-shielding film for optical element and optical element having light-shielding film

ABSTRACT

A light-shielding film for optical element includes at least a resin and a colorant. The light-shielding film for optical element has an average extinction coefficient of 0.03 or more and 0.15 or less as an average of extinction coefficients of the whole light-shielding film for light having wavelengths ranging from 400 to 700 nm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-shielding film for opticalelement that is applied to an optical apparatus, such as a camera,binoculars, a microscope, or a semiconductor exposure apparatus, andrelates to an optical element.

2. Description of the Related Art

A light-shielding film for optical element is a coating film formed on asurface of, for example, glass or plastic. The optical element may be alens, a prism, or another optical glass element, but, in thisspecification, the light-shielding film will be described using a lensas an example.

As shown in FIG. 1, the light-shielding film 1 for optical element isformed on an appropriate outer portion of a lens 2 serving as theoptical element. Some of incident light, such as incident light 3,passes through the lens 2 as transmitted light 4. On the other hand,oblique incident light, such as incident light 5, strikes thelight-shielding film 1. If the light-shielding film 1 is not provided,the light that struck the outer portion of the lens 2 isinner-surface-reflected and exits to the outside of the lens 2 asimage-unrelated inner-surface-reflected light 6, which causes flare,ghost, etc. to deteriorate the image quality. Occurrence of theinner-surface-reflected light 6 due to the oblique incident light 5 canbe reduced by providing the light-shielding film 1, which can preventflare and ghost to inhibit disadvantageous effects on an image.

FIG. 2 is a schematic view illustrating how inner-surface-reflectedlight travels. As shown in FIG. 2, incident light 3 travels in the lens2 and becomes first reflected light 8 at the interface 21 with thelight-shielding film 1. The transmitted light 9 traveled in thelight-shielding film 1 becomes second reflected light 10 at theinterface 22 between the light-shielding film 1 and air. Therefore, inthe inner-surface reflection, the first reflection light 8 and thesecond reflection light 10 are involved.

Recently, along with a reduction in lens size and an improvement inperformance, the designed clearance between a lens and a lens barrel hasbeen reduced. Accordingly, if a light-shielding film for optical elementhas a thickness that is equivalent to those of existing films, since theclearance is small, the lens may not be incorporated into a lens barrel.Therefore, in order to set a lens provided with a light-shielding filminto a narrow clearance, the light-shielding film for optical elementneeds to be reduced in the thickness. In addition, a thinnerlight-shielding film can decrease the stress, resulting in a reductionin deformation of the lens.

Japanese Patent Publication No. 47-32419 describes an example of thelight-shielding film that absorbs light with coal tar, carbon black, anddye while improving the refractive index with the coal tar. JapanesePatent Laid-Open No. 2007-183444 describes an example of thelight-shielding film that absorbs light with coal tar and dye whileimproving the refractive index with the coal tar. Japanese PatentLaid-Open No. 07-82510 describes in this coating film, the content ofthe inorganic black particle is 10 to 60 parts by weight, because acontent not larger than 10 parts by weight cannot sufficiently increasethe refractive index of the light-shielding film, resulting in a largedifference between the refractive indices of the light-shielding filmand an optical element not to inhibit inner-surface reflection.

In order to inhibit the above-described inner-surface reflection, it isnecessary to decrease the first reflected light 8 and the secondreflected light 10. In order to decrease the reflection at the firstinterface, it is effective to decrease the difference between therefractive indices of the light-shielding film 1 and the lens 2. Thatis, it is necessary that the light-shielding film for optical elementhave a refractive index near that of the lens. In order to decrease thereflection at the second interface, it is necessary to make thelight-shielding film 1 sufficiently black for absorbing the transmittedlight 9 that transmitted to the light-shielding film 1. That is, thelight-shielding film 1 needs to have a degree of blackness that cansufficiently absorb the transmitted light entered inside thelight-shielding film.

However, an increase in absorption by increasing the degree of blacknessof the light-shielding film 1 causes a problem in that the firstreflected light 8 increases. The absorption of the light-shielding film1 can be also increased by increasing the thickness of thelight-shielding film 1, but an increase in the thickness inhibits theabove-described reduction in lens size and improvement in performance.The light-shielding film for optical element described in JapanesePatent Publication No. 47-32419 contains 15 wt % or more and 36 wt % orless of carbon black and 15 wt % or more and 36 wt % or less of a dye,which sufficiently increases the refractive index and reduces thedifference between the refractive indices of the light-shielding filmand the lens. However, since the absorption of the light-shielding filmis high, the reflection at the interface between the lens and thelight-shielding film cannot be sufficiently inhibited.

In the light-shielding film for optical element described in JapanesePatent Laid-Open No. 2007-183444, the refractive index is increased bycoal tar to reduce the difference between the refractive indices of thelight-shielding film and the lens. In addition, the absorption is smalldue to the low concentration of the dye, which can reduce the reflectionat the interface between the lens and the light-shielding film. However,since the absorption is small, in order to inhibit the reflection at theinterface between the light-shielding film and air, the thickness of thefilm must be increased.

In the light-shielding film for optical element described in JapanesePatent Laid-Open No. 07-82510, the inorganic black particle content iscontrolled in the range of 10 to 60 parts by weight in order tosufficiently increase the refractive index of the light-shielding film.This light-shielding film can have a high refractive index, but thedegree of absorption of the light-shielding film is low. Therefore, thefirst reflected light 8, which is light reflected at the interfacebetween the light-shielding film and air, cannot be sufficientlyinhibited.

SUMMARY OF THE INVENTION

The present invention provides a light-shielding film for opticalelement, having a small thickness and being low in inner-surfacereflection, and also provides an optical element having thelight-shielding film, being low in inner-surface reflection.

The light-shielding film for optical element of the present inventioncontains at least a resin and a colorant and has an average extinctioncoefficient of 0.03 or more and 0.15 or less as an average of extinctioncoefficients of the whole light-shielding film for light havingwavelengths ranging from 400 to 700 nm (when the light-shielding film iscomposed of two or more layers, an average extinction coefficient of thelight-shielding film as a whole).

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a light-shielding film foroptical element formed on a lens.

FIG. 2 is a schematic view illustrating how inner-surface-reflectedlight travels in a light-shielding film.

FIG. 3 is a schematic view illustrating a light-shielding film in whichthe dye concentration on the side adhering to a lens is lower than thatas a whole.

FIG. 4A is a schematic view illustrating a method of measuringinner-surface reflectance of a trigonal prism.

FIG. 4B is a schematic view illustrating the method of measuringinner-surface reflectance of the trigonal prism.

FIG. 4C is a schematic view illustrating the method of measuringinner-surface reflectance of the trigonal prism.

FIG. 5 is a schematic view illustrating a method of evaluatingappearance of a trigonal prism.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will be described below.

First, a constitution of a light-shielding film for optical elementaccording to the present invention will be described. Then, aconstitution of materials of the light-shielding film showingsatisfactory inhibition of inner-surface reflection, even if it isreduced in thickness, will be described.

Constitution of Light-Shielding Film for Optical Element

The light-shielding film for optical element according to the presentinvention contains at least a resin and a colorant and has an averageextinction coefficient of 0.03 or more and 0.15 or less as an average ofextinction coefficients of the whole light-shielding film for lighthaving wavelengths ranging from 400 to 700 nm.

The principle of the inner-surface reflection will be described in moredetail with reference to FIG. 2. As described above, the inner-surfacereflection mainly occurs at two interfaces 21 and 22. That is, theincident light 3 travels in the lens 2 and becomes first reflected light8 at the interface 21 between the lens 2 and the light-shielding film 1.The transmitted light 9 traveled in the light-shielding film 1 becomessecond reflected light 10 at the interface 22 between thelight-shielding film 1 and air.

The first reflected light 8 can be reduced by decreasing the differencebetween the refractive indices of the light-shielding film 1 and thelens 2. The reason for that inner-surface reflection is reduced bydecreasing the difference between the refractive indices is, as shown inEquation (1) below, the reflectance R of the interface between thelight-shielding film 1 and the lens 2 is determined by the differencebetween the refractive index n₀ of the lens 2 and the refractive indexn₁ of the light-shielding film 1, and the smaller the difference is, thesmaller the reflectance R is. Furthermore, since the light-shieldingfilm 1 is black and absorbs light, it is necessary to determine thereflectance with considering the absorbance. When the absorbance of thelight-shielding film is brought into consideration, the reflectance R isrepresented by an equation considering the extinction coefficient(attenuation coefficient) k as shown by Equation (1).

In this specification, the extinction coefficient k is a factor defininga quantity of light absorbed by a material.

$\begin{matrix}{R = {\frac{{{N_{1} - N_{0}}}^{2}}{{{N_{1} + N_{0}}}^{2}} = \frac{\left( {n_{1} - n_{0}} \right)^{2} + k^{2}}{\left( {n_{1} + n_{0}} \right)^{2} + k^{2}}}} & {{Equation}\mspace{14mu} (1)}\end{matrix}$

In the equation, N represents the complex refractive index of arefractive index n. The refractive index n of a light-shielding film isrepresented by the complex refractive index N shown by Equation (2)obtained by adding the extinction coefficient k representing theabsorption factor to the imaginary part i.

N=n−ik  Equation (2)

n represents the refractive index, and i represents the imaginary part.

The reflectance R is increased with the extinction coefficient k, whenthe extinction coefficient k representing the absorption factor k isconsidered.

That is, in order to reduce the inner-surface reflection at theinterface between the lens and the light-shielding film having alight-absorbing property, it is necessary to reduce the differencebetween refractive indices of the light-shielding film and the lens andto reduce the value of extinction coefficient k. Since the bleedingrange of light is about one fourth of the wavelength, the complexrefractive index N can be increased by reducing the extinctioncoefficient in the area approximately 0.1 to 0.175 μm from the lensinterface as low as possible.

The second reflected light 10 can be reduced by absorbing thetransmitted light 9 traveling in the light-shielding film.

In the light-shielding film of the present invention, the extinctioncoefficient of the whole light-shielding film (when the light-shieldingfilm is composed of two or more layers, the extinction coefficientrepresents the average of the extinction coefficients of the layers) is0.03 or more and 0.15 or less, preferably 0.03 or more and 0.1 or less.When the extinction coefficient is smaller than 0.03, the quantity ofreflected light at the interface between the light-shielding film andair is large, resulting in a deterioration in antireflection function.When the extinction coefficient is larger than 0.15, reflection at theinterface between the lens and the light-shielding film is large. Aslong as the light-shielding film has an extinction coefficient of 0.03or more and 0.15 or less, the light-shielding film may contain dye aloneor may contain a small amount of pigment having a high extinctioncoefficient in addition to dye. Furthermore, the light-shielding filmmay contain inorganic black particles having a d-line refractive indexof 2.2 or more and 3.5 or less alone as long as the extinctioncoefficient of the light-shielding film is 0.03 or more and 0.15 orless.

The light-shielding film is used in contact with an optical element. Theextinction coefficient of the light-shielding film on the side that isin contact with the optical element can be smaller than the averageextinction coefficient of the whole light-shielding film. Specifically,the extinction coefficient of the light-shielding film 1 can be lower onthe side where the light-shielding film 1 and the lens 2 are in contactthan the average extinction coefficient of the whole light-shieldingfilm.

The extinction coefficient of the light-shielding film on the side beingin contact with the lens can be specifically decreased, for example, byforming the light-shielding film with two or more layers containingdifferent concentrations of dye or by adding both dye and pigment to thelight-shielding film, but the method is not limited thereto.

For example, the light-shielding film 1 composed of two or morelight-shielding layers containing different concentrations of dye can beobtained, as shown in FIG. 3, by forming a light-shielding layer 11containing dye in a lower concentration and, after hardening of thelayer, forming a light-shielding layer 12 containing dye in a higherconcentration. Here, the thickness of the light-shielding layer 11containing a lower concentration of the dye can be larger than onefourth of the wavelength of light (100 nm or more, when the wavelengthis 400 nm) considering the bleeding distance of light, that is, thethickness can be about 0.1 μm or more considering the wavelength rangeof visible light. The method of forming a difference in concentration ofdye is not limited to the above.

In the light-shielding film for optical element of the presentinvention, the ratio of a minimum transmittance to a maximumtransmittance, (minimum transmittance)/(maximum transmittance), forlight with wavelengths ranging from 400 to 700 nm can be 0.7 or more. Ifthe ratio is smaller than 0.7, which causes occurrence of unevenness ofinner-surface reflection depending on light wavelength and also causes adeterioration in color tone to degrade the appearance of thelight-shielding film.

The average thickness of the light-shielding film for optical element ofthe present invention can be 2 μm or more and 30 μm or less, preferably2 μm or more and 10 μm or less. When the thickness is 10 μm or less, theeffect of preventing inner-surface reflection can be higher than that ofa known coating film containing a small amount of dye, and even when thethickness is 2 μm, the effect of preventing inner-surface reflection canbe maintained. However, when the thickness of the light-shielding filmis smaller than 2 μm, as described above with reference to FIG. 2, sincelight reflection 10 occurs at the interface between the light-shieldingfilm and air, the inner-surface reflection becomes large. If thethickness of the light-shielding film is larger than 10 μm, since lightis sufficiently absorbed, the inner-surface reflection is low.Therefore, the thickness may be 30 μm or more as long as it does notcause a problem from the standpoint of lens design. However, a thicknessof 30 μm or more may cause a problem in optical design, such that thelens cannot be incorporated into a lens barrel.

Material Constitution

Materials constituting the light-shielding film of the present inventionwill now be described.

The light-shielding film of the present invention contains at least aresin, a colorant, and non-black particles. The colorant is dye, amixture of dye and pigment, or inorganic black particles having a d-linerefractive index of 2.2 or more and 3.5 or less and giving an extinctioncoefficient of 0.03 or more and 0.15 or less when they are contained ina light-shielding film. The inorganic black particles have high lightresistance compared with dye and are therefore suitable for applicationthat requires high light resistance. Note that the term “degree ofblackness” in the present invention is a ratio of a minimumtransmittance to a maximum transmittance, (minimumtransmittance)/(maximum transmittance), for light having wavelengthsranging from 400 to 700 nm. The black pigment and the inorganic blackparticles in the present invention each have a degree of blackness of0.7 or more.

The pigment used in the present invention is particles insoluble tosolvents and is a black material that absorbs visible light havingwavelengths ranging from 400 to 700 nm. The pigment can have a highaverage extinction coefficient. Examples of the material that isinsoluble to solvents and is black and has a high extinction coefficientinclude, but not limited to, black pigments composed of at least oneselected from the group consisting of carbon black, copper-manganesecomplex oxide, titanium black, and copper oxide.

The average particle diameter of the pigment can be 0.1 μm or more and10 μm or less. Here, the average particle diameter of the pigment isthat of actual sizes of particles present in a film, that is, when thepigment particles are aggregated, the size is that of the aggregate.Therefore, the primary particle diameter of the pigment may be smallerthat 0.1 μm, as long as the average particle diameter after aggregationis 0.1 μm or more. The pigment is usually contained in a film in anaggregated form. Accordingly, the average particle diameter may besmaller than 0.1 μm as long as the average particle diameter afteraggregation is 0.1 μm or more. The pigment is usually contained in afilm in an aggregated form, but if the average particle diameter afteraggregation is smaller than 0.1 μm, the compatibility of the pigmentwith a resin is increased, which allows the particles to easily reachthe side being in contact with the lens. If the pigment reaches theinterface with the lens, since the extinction coefficient of the pigmentis high, the extinction coefficient of the interface is increased,resulting in an increase in inner-surface reflection. On the other hand,when the average particle size after aggregation is larger than 10 μm,the thickness of the light-shielding film is increased. This may cause aproblem that the lens cannot be incorporated into a lens barrel.

The dye is a material that absorbs visible light having wavelengthsranging from 400 to 700 nm and is soluble to an appropriate solvent.Organic materials that are not classified as dye are also included aslong as they satisfy the requirements. In order to regulate the ratio ofa minimum transmittance to a maximum transmittance, (minimumtransmittance)/(maximum transmittance), of the light-shielding film forlight having wavelengths ranging from 400 to 700 nm to 0.7 or more, onekind of dye may be used, or two or more kinds of dye, such as black,red, yellow, or blue dye, may be mixed to control absorption wavelength.The dye can be azo dye, which is abundant in colors, but may beanthraquinone dye, phthalocyanine dye, stilbenze dye, pyrazolone dye,thiazole dye, carbonium dye, or azine dye. Furthermore, dye containing ametal, such as chromium, cobalt, or copper, can have increased toughnesssuch as light resistance, water resistance, and heat resistance and canbe used.

The content of the dye contained in the light-shielding film of thepresent invention is, when the dye is used alone, 13 wt % or more and 50wt % or less, preferably 13 wt % or more and 40 wt % or less. Ingeneral, when dye is used for dyeing, the dye content is 10 wt % orless. However, in order to obtain a light-shielding property having ahigh extinction coefficient of 0.03, a dye content of 13 wt % or more isnecessary. Since the content of the dye is high, the dye may not bedissolved in a resin, but it is not a problem in the present invention.However, a dye content of higher than 50 wt % deteriorates the solventresistance. Therefore, the content is usually 50 wt % or less.

The inorganic black particles that have a d-line refractive index of 2.2or more and 3.5 or less and give an extinction coefficient of 0.03 ormore and 0.15 or less when they are contained in a light-shielding filmmay be contained in the light-shielding film of the present invention asa single kind of particles or two or more kinds of particles. Examplesof the material for the inorganic black particles include TiN, titaniacovered with carbon black, titania covered with titanium black, zirconiacovered with carbon black, and zirconia covered with titanium black.

The inorganic black particles of the present invention can have anaverage particle diameter of 10 nm or more and 100 nm or less,preferably 10 nm or more and 20 nm or less, and the content of particleshaving a particle diameter of 100 nm or more can be 1% or less. Theinorganic black particles may have a smaller average particle diameter,but it is difficult to actually disperse particles having a particlediameter of 10 nm or less. On the other hand, if the average particlediameter of the inorganic black particles is 100 nm or more, scatteringoccurs to deteriorate the inner-surface reflection. In addition, if thecontent of particles having a diameter of 100 nm or more is higher than1% of the inorganic black particles, scattering occurs to deterioratethe inner-surface reflection.

When the inorganic black particles are made of TiN alone, the contentthereof can be 12 wt % or more and 45 wt % or less. If the TiN contentis 12 wt % or less, the refractive index is not sufficiently increased,resulting in deterioration in the inner-surface reflection, but if theTiN content is higher than 45 wt %, the adhesive property of the film isdeteriorated.

When the inorganic black particles having a d-line refractive index of2.2 or more and 3.5 or less are made of titania covered with carbonblack or titanium black or zirconia covered with carbon black ortitanium black alone, the content thereof can be 10 wt % or more and 45wt % or less. If the content is 10 wt % or less, the refractive index isnot sufficiently increased, resulting in deteriorate in theinner-surface reflection, but if the content is higher than 45 wt %, theadhesive property of the film is deteriorated.

A resin having good adhesiveness with a base material, for example, alens can be used. In order to improve the refractive index of the filmas a whole, a resin itself having a high refractive index can be used.Examples of the resin having a high refractive index and goodadhesiveness with a lens include epoxy resins. Other examples of theresin include, but not limited to, urethane resins, acrylic resins,melamine resins, and vinylidene chloride polymers.

The content of the resin contained in the light-shielding film of thepresent invention can be 10 wt % or more and 60 wt % or less, preferably15 wt % or more and 30 wt % or less, as a ratio by weight when the filmis formed. If the resin content is 10 wt % or less, the durability ofthe film is disadvantageously reduced.

The light-shielding film of the present invention can contain, as amaterial for improving the refractive index of the light-shielding film,non-black particles having an average particle diameter of 100 nm orless and a refractive index (nd) of 2.2 or more. If all the materialsfor improving the refractive index are black particles, the degree ofblackness cannot be controlled. However, in order to control the degreeof blackness, a small number of black particles having a refractiveindex (nd) of 2.2 or more may be contained in the light-shielding film.When the refractive index of the non-black particles is lower than 2.2,the refractive index of the light-shielding film cannot be sufficientlyincreased. Here, the particle diameters of the non-black particles arethose of actual sizes of the particles present in the light-shieldingfilm, that is, when the non-black particles are aggregated, the size isthat of the aggregate. On this occasion, all the non-black particles canhave particle diameters of 100 nm or less and can be uniformlydispersed. Even if the average particle diameter is small, if aggregatedparticles or coarse particles larger than 100 nm are contained,scattering occurs to reflect the refracted light that has entered thelight-shielding film from the lens side, without the light-shieldingfilm does not absorb the light. Examples of the non-black particlessatisfying these properties include, but not limited to, nano-dispersedtitania, zirconia, alumina, yttria, or ceria fine particles. Thenon-black particles can be titania, zirconia, or a mixture thereof.Furthermore, coal tar having a high refractive index may be used as amaterial for improving the refractive index.

The light-shielding film for optical element of the present inventionmay contain particles of a surface reflection preventing agent such assilica, quartz, or sericite. When the light-shielding film containstransparent fine particles of, for example, silica, quartz, or sericite,it is possible to form wrinkles or asperities on the surface, resultingin a decrease in reflection at the interface between the film and air.The content of other components contained in the light-shielding film ofthe present invention can be 0.1 wt % or more and 30 wt % or less,preferably 10 wt % or more and 20 wt % or less as a ratio by weight inthe film.

Process of Producing Light-Shielding Film for Optical Element

The light-shielding film for optical element of the present invention isobtained by hardening a light-shielding coating for optical element.

The light-shielding coating for optical element contains at least acolorant, a resin, and a refractive-index-improving material. Thelight-shielding coating may further contain an additional component aslong as the effects of the present invention are not impaired.

The light-shielding coating for optical element is obtained bydispersing the colorant, the resin, and the refractive-index-improvingmaterial by an appropriate mixing and dispersing process. Examples ofthe mixing and dispersing process include, but not limited to, collisiondispersion, planetary rotation, and mixing/dispersing using a rollcoater or a mixer.

The colorant can have high compatibility with a solvent and excellenttoughness such as light resistance, water resistance, and heatresistance. An example such a colorant is azo dye containing chromium.

The non-black particles having an average particle diameter of 100 nm orless and a refractive index (nd) of 2.2 or more, which is an example ofthe refractive-index-improving material, may be a commercially availableone. Examples of the process of producing slurry include a method ofdispersing nano-fine particles with a bead mill or collision dispersionapparatus and a sol-gel method. In the slurry production, an appropriatesurface treating agent or dispersant may be used.

The resin can have a high refractive index and high adhesiveness to abase material, such as a lens. An example of the resin is an epoxyresin.

Any solvent that can disperse the pigment and therefractive-index-improving material particles and can dissolve the dyecan be used. Examples of the solvent include, but not limited to,toluene, hexane, cyclohexane, xylene, 1-butanol, butyl acetate, ethylacetate, methyl isobutyl ketone (MIBK), and propylene glycol monomethylether (PGME).

The light-shielding coating may further contain additives, such as ahardener for hardening the resin, a coupling agent, a dispersant, anantiseptic agent, an antioxidant, and an antifungal agent, as additionalcomponents.

The optical element of the present invention is characterized by havingthe light-shielding film for optical element described above. Examplesof the optical element include cameras, binoculars, microscopes,semiconductor exposure apparatuses, cameras for mobile phones, andbroadcast equipment.

EXAMPLES

Preferred examples of the present invention will be described below.

Examples 1 to 24

Preparation of light-shielding coatings for optical element according toExamples 1 to 24, production of light-shielding films for opticalelement, and evaluation of optical properties were conducted as follows.

Preparation of Light-Shielding Coating for Optical Element

Tables 1 to 6 show resins, dyes, black pigments, non-black particles,solvents, coupling agents, hardeners, and their mixing ratiosconstituting light-shielding coatings for optical element A, B, C, D, E,F, G, H, I, J, K, L, M, N, O, R, S, T, U, V, W, X, Y, and AD.Light-shielding coating and light-shielding film for optical element Awas used in Example 1; light-shielding coating and light-shielding filmfor optical element B was used in Example 2; light-shielding coating andlight-shielding film for optical element C was used in Example 3;light-shielding coating and light-shielding film for optical element Dwas used in Example 4; light-shielding coating and light-shielding filmfor optical element E was used in Example 5; light-shielding coating andlight-shielding film for optical element F was used in Example 6;light-shielding coating and light-shielding film for optical element Gwas used in Example 7; light-shielding coating and light-shielding filmfor optical element H was used in Example 8; light-shielding coating andlight-shielding film for optical element I was used in Example 9;light-shielding coating and light-shielding film for optical element Jwas used in Example 10; light-shielding coating and light-shielding filmfor optical element K was used in Example 11; light-shielding coatingand light-shielding film for optical element L was used in Example 12;light-shielding coating and light-shielding film for optical element Mwas used in Example 13; light-shielding coating and light-shielding filmfor optical element N was used in Example 14; light-shielding coatingand light-shielding film for optical element O was used in Example 15;light-shielding coating and light-shielding film for optical element Rwas used in Example 16; light-shielding coating and light-shielding filmfor optical element S was used in Example 17; light-shielding coatingand light-shielding film for optical element T was used in Example 18;light-shielding coating and light-shielding film for optical element Uwas used in Example 19; light-shielding coating and light-shielding filmfor optical element V was used in Example 20; light-shielding coatingand light-shielding film for optical element W was used in Example 21;light-shielding coating and light-shielding film for optical element Xwas used in Example 22; light-shielding coating and light-shielding filmfor optical element Y was used in Example 23; and light-shieldingcoating and light-shielding film for optical element AD was used inExample 24.

The process of preparing the light-shielding coating for optical elementwill be described in detail using the light-shielding coating foroptical element A as an example. First, an epoxy resin (4 g, Epicoat828: Japan Epoxy Resins), a black dye (4 g), a red dye (2.9 g), a yellowdye (0.375 g), titania (2 g, ND139: Teica) serving as non-blackparticles, a solvent (24 g, propylene glycol monomethyl ether: KishidaChemical), and a coupling agent (1.2 g, KBM-403: Shin-Etsu Chemical)were weighed and placed in a ball mill pot. Subsequently, five magneticballs each having a diameter of 20 mm were put in the ball mill pot. Theball mill pot containing weighed coating components and the magneticballs was set to a roll coater, followed by stirring at 66 rpm for 72hours to obtain a light-shielding coating for optical element.

The dyes used were as follows.

The black dye was selected from VALIFAST BLACK 1821 (Orient Chemical),VALRFAST BLACK 3810 (Orient Chemical), Oil Black HBB (Orient Chemical),and Aizen Spilon Black MHS-Liquid (Hodogaya Chemical).

The red dye was selected from VALIFAST RED 3320 (Orient Chemical) andAizen Spilon Red BEH S-Liquid (Hodogaya Chemical).

The yellow dye was selected from OIL YELLOW 129, VALIFAST YELLOW 3108,and Aizen Spilon Yellow RH S-Liquid (Hodogaya Chemical).

Production of Light-Shielding Film for Optical Element

A light-shielding film was formed from the light-shielding coating. Ahardener (4 g, Adeca hardener EH551CH: Adeca) was added to the totalamount of the light-shielding coating for optical element, and themixture was stirred with a roll coater at 66 rpm for 30 minutes.

The resulting light-shielding coating for optical element/hardenersolution was applied onto a prism for evaluation at a thickness of 2 μm,followed by drying at room temperature for 60 minutes. Thelight-shielding coating for optical element after the drying washardened at 80° C. for 120 minutes in a heating furnace to obtain alight-shielding film for optical element.

Evaluation of Optical Properties

Method of measuring average extinction coefficient A sample formeasuring average extinction coefficient was prepared by forming alight-shielding film for optical element on a flat glass plate 20 mm inwidth, 50 mm in length, and 1 mm in thickness. The light-shielding filmfor optical element was formed on the upper surface of the flat glassplate so as to have a thickness of 1 μm. Then, transmittance wasmeasured with a spectrometer (U-4000: Hitachi High-Technologies). Thesample having the light-shielding film for measuring extinctioncoefficient was set to the spectrometer, and transmittance was measuredat 1-nm intervals for visible light having wavelengths ranging from 400to 700 nm, defining the transmittance of the flat glass plate as 100%.The average transmittance of the extinction-coefficient-measuring samplefor the light having wavelengths ranging from 400 to 700 nm wascalculated by dividing transmittance for each of the wavelengths ranging400 to 700 nm by 300, which is the number of measurement points.

The extinction coefficient was calculated by the following Equations(3), (4), and (5) using the average transmittance I measured with thespectrometer. The optical density (OD) shown by Equation (3) representsabsorbance and is a value obtained by taking −log of the valuecalculated by dividing the average transmittance I by the transmittanceI₀ of the flat glass plate (100%). The absorbance coefficient α shown byEquation (4) represents the quantity of absorbed light per unit length,obtained by dividing the absorbance OD by the thickness L of thelight-shielding film. The extinction coefficient k shown by Equation (5)is a value obtained by multiplying the absorbance coefficient α by awavelength λ for nondimensionalization.

OD=−log(I/I ₀)  Equation (3)

α=2.303×OD/L  Equation (4)

k=α×λ/4π  Equation (5)

Method of Measuring Inner-Surface Reflectance

The inner-surface reflectance was measured using an ASP spectrometer(ASP-32: Bunko Keiki) as shown in FIGS. 4A to 4C. As the sample for themeasurement, a trigonal prism 14 made of S-LAH53 (nd=1.805) and having asize in which the sides forming a right angle therebetween were each 30mm and thickness was 10 mm was used.

FIG. 4A is a schematic view illustrating a method of measuringinner-surface reflectance when the incident angle b to the trigonalprism 14 is 90°. First, a method using the ASP spectrometer will bedescribed with reference to FIG. 4A. Since the ASP spectrometer canfreely change the angle between the sample and the detector,inner-surface reflectance can be measured for each incident angle. Thelight emitted from the ASP spectrometer enters the trigonal prism 14 atan incident angle b of 90°. On this occasion, refraction of light occursdue to the difference in refractive indices of air and the prism. Theincident angle c after the refraction is 68.13°. The angle e, after therefraction, to the incident angle d is calculated by the followingEquation (6):

n=sin d/sin e  Equation (6)

The incident angle c was also calculated from the angle e after therefraction.

Subsequently, the light refracted by the trigonal prism 14 strikes thebottom surface of the trigonal prism 14 and is reflected to the outsideof the trigonal prism 14. The intensity of this reflected light wasdetected over the visible light region, from 400 to 700 nm, with adetector. The background was determined using a trigonal prism 14 havinga mirror bottom to which no film was applied. The inner-surfacereflectance when the light-shielding film for optical element wasapplied to the brushed bottom of a trigonal prism 14 was measured. Theinner-surface reflectance values shown in Tables 7 to 12 are averages ofthe results obtained by measuring inner-surface reflectance at 1-nmintervals for light having wavelengths ranging from 400 to 700 nm.

Similarly, FIG. 4B is a schematic view illustrating a method ofmeasuring inner-surface reflectance when the incident angle b to thetrigonal prism 14 was 45°. When the incident angle b to the trigonalprism 14 was 45°, the incident angle c after the refraction was 45°without change.

Similarly, FIG. 4C is a schematic view illustrating a method ofmeasuring inner-surface reflectance when the incident angle b to thetrigonal prism 14 was 30°. When the incident angle b to the trigonalprism 14 was 30°, the incident angle c after the refraction was 36.73°.

From correlation with the results of incorporation into mirror-barreltests, a light-shielding film can be determined to have a satisfactoryinner-surface reflectance when the inner-surface reflectance at anincident angle of 68.13° is 1% or less, the inner-surface reflectance atan incident angle of 45° is 0.07% or less, and the inner-surfacereflectance at an incident angle of 36.73° is 0.05% or less.

Method of Measuring Degree of Blackness

The degree of blackness was determined by measuring transmittance forlight having wavelengths from 400 to 700 nm using a spectrophotometerand substituting a minimum transmittance and a maximum transmittance inthe results measured for the light having wavelengths from 400 to 700 nminto the following Equation (7) to calculate the ratio thereof.

Degree of blackness=(minimum transmittance)/(maximumtransmittance)  Equation (7)

The sample for measuring the degree of blackness was prepared by forminga light-shielding film for optical element on a flat glass plate 20 mmin width, 50 mm in length, and 1 mm in thickness. The light-shieldingfilm for optical element was formed on the upper surface of the flatglass plate so as to have a thickness of 1 μm. In general, a degree ofblackness of 0.7 or more is satisfactory.

Method of Evaluating Appearance

The evaluation of appearance was performed by irradiation with light of60 W from an irradiator, as shown in FIG. 5. As the sample formeasurement, a trigonal prism 14 made of S-LAH53 (nd=1.805) and having asize in which the sides forming a right angle therebetween were each 30mm and thickness was 10 mm was used. The light-shielding film was formedon the bottom of the trigonal prism 14, and the bottom was irradiatedwith light. The reflected light was visually observed by 15 inspectors.Roughness and color tone were evaluated as observation items.

Performance in the State Incorporated in Lens Barrel

The light-shielding film for optical element was formed on a telescopiclens, and the lens was incorporated into a lens barrel. The telescopiclens provided with the light-shielding film for optical element of thepresent invention was incorporated into a camera, and shooting wasperformed using the camera. The shot images were displayed for visuallyinspecting occurrence of flare and ghost.

TABLE 1 Light-shielding Light-shielding Light-shielding Light-shieldingcoating and coating and coating and coating and film for optical filmfor optical film for optical film for optical element: A element: Belement: C element: D Light-shielding Resin material epoxy epoxy epoxyepoxy coating for content (g) 4 4 4 4 optical element Dye material azodye azo dye azo dye azo dye model No. (1)dye black (1)dye black (1)dyeblack (1)dye black (2)dye red (2)dye red (2)dye red (2)dye red (3)dyeyellow (3)dye yellow (3)dye yellow (3)dye yellow content (g) (1)4 (1)6(1)4 (1)4 (2)2.9 (2)4.35 (2)2.9 (2)2.9 (3)0.375 (3)0.562 (3)0.375(3)0.375 total dye content (g) 7.275 10.912 7.275 7.275 Black material —— carbon black carbon black pigment particle diameter (μm): — — 0.1 10after aggregation content (g) 0 0 2 2 Non-black material titania titaniatitania titania particle (dispersed in (dispersed in (dispersed in(dispersed in propylene glycol propylene glycol propylene glycolpropylene glycol monomethyl ether, monomethyl ether, monomethyl ether,monomethyl ether, solid content: solid content: solid content: solidcontent: 25 wt %) 25 wt %) 25 wt %) 25 wt %) particle diameter (nm) 2020 20 20 content (g): solid 2 2 2 2 content weight Solvent materialpropylene glycol propylene glycol propylene glycol propylene glycolmonomethyl ether monomethyl ether monomethyl ether monomethyl ethercontent (g) 24 24 24 24 Coupling material epoxy-based epoxy-basedepoxy-based epoxy-based agent silane coupling silane coupling silanecoupling silane coupling agent agent agent agent content (g) 1.2 1.2 1.21.2 Surface- material — — — — reflection content (g) — — — — inhibitortotal content (g) 0 0 0 0 Hardener material amine base amine base aminebase amine base content (g) 4 4 4 4 Light-shielding dye content ratio(%) 39.4 49.3 35.5 35.5 film for Thickness (μm) 5 5 5 5 optical element

TABLE 2 Light-shielding Light-shielding Light-shielding Light-shieldingcoating and coating and coating and coating and film for optical filmfor optical film for optical film for optical element: E element: Felement: G element: H Light-shielding Resin material epoxy epoxy epoxyepoxy coating for content (g) 4 4 4 4 optical element Dye material azodye azo dye azo dye azo dye model No. (1)dye black (1)dye black (1)dyeblack (1)dye black (2)dye red (2)dye red (2)dye red (2)dye red (3)dyeyellow (3)dye yellow (3)dye yellow (3)dye yellow content (g) (1)4 (1)4(1)4 (1)9 (2)2.9 (2)2.9 (2)2.9 (2)6.5 (3)0.375 (3)0.375 (3)0.375 (3)0.84total dye content (g) 7.275 7.275 7.275 16.34 Black material Cu—Fe—Mn Tiblack Copper oxide — pigment complex oxide particle diameter (μm): 0.10.2 0.2 — after aggregation content (g) 2 2 2 0 Non-black materialtitania titania titania titania particle (dispersed in (dispersed in(dispersed in (dispersed in propylene glycol propylene glycol propyleneglycol propylene glycol monomethyl ether, monomethyl ether, monomethylether, monomethyl ether, solid content: solid content: solid content:solid content: 25 wt %) 25 wt %) 25 wt %) 25 wt %) particle diameter(nm) 20 20 20 20 content (g): solid 2 2 2 2 content weight Solventmaterial propylene glycol propylene glycol propylene glycol propyleneglycol monomethyl ether monomethyl ether monomethyl ether monomethylether content (g) 24 24 24 24 Coupling material epoxy-based epoxy-basedepoxy-based epoxy-based agent silane coupling silane coupling silanecoupling silane coupling agent agent agent agent content (g) 1.2 1.2 1.21.2 Surface- material — — — — reflection content (g) — — — — inhibitortotal content (g) 0 0 0 0 Hardener material amine base amine base aminebase amine base content (g) 4 4 4 4 Light-shielding dye content ratio(%) 35.5 35.5 35.5 59.3 film for Thickness (μm) 5 5 5 5 optical element

TABLE 3 Light-shielding Light-shielding Light-shielding Light-shieldingcoating and coating and coating and coating and film for optical filmfor optical film for optical film for optical element: I element: Jelement: K element: L Light-shielding Resin material epoxy epoxy epoxyepoxy coating for content (g) 4 4 4 4 optical element Dye material azodye (1)-(3)azo dye (1)-(3)azo dye (1)-(3)azo dye (4)phthalocyanine dye(4)phthalocyanine dye (4)phthalocyanine dye model No. (1)dye black(1)dye black (1)dye black (1)dye black (2)dye red (2)dye red (2)dye red(2)dye red (3)dye yellow (3)dye yellow (3)dye yellow (3)dye yellow(4)dye blue (4)dye blue (4)dye blue content (g) (1)4 (1)0.55 (1)2.22(1)0.55 (2)2.9 (2)1.36 (2)5.52 (2)1.36 (3)0.375 (3)0.55 (3)2.22 (3)0.55(4)2.17 (4)8.82 (4)2.17 total dye content (g) 7.275 4.63 18.78 4.63Black material iron oxide (Fe₂O₃) — — — pigment particle diameter (μm):0.1 — — — after aggregation content (g) 2 0 0 0 Non-black materialtitania titania titania zirconia particle (dispersed in (dispersed in(dispersed in propylene glycol propylene glycol propylene glycolmonomethyl ether, monomethyl ether, monomethyl ether, solid content:solid content: solid content: 25 wt %) 25 wt %) 25 wt %) particlediameter (nm) 20 20 20 10 content (g): solid 2 5 5 5 content weightSolvent material propylene glycol propylene glycol propylene glycolpropylene glycol monomethyl ether monomethyl ether monomethyl ethermonomethyl ether content (g) 24 12 12 12 Coupling material epoxy-basedepoxy-based epoxy-based epoxy-based agent silane coupling silanecoupling silane coupling silane coupling agent agent agent agent content(g) 1.2 1.2 1.2 1.2 Surface- material — (1)nano-silica (1)nano-silica(1)nano-silica reflection (hydrophilic) (hydrophilic) (hydrophilic)inhibitor (2)nano-silica (2)nano-silica (2)nano-silica (hydrophobic)(hydrophobic) (hydrophobic) (3)sericite (3)sericite (3)sericite(4)quartz (4)quartz (4)quartz content (g) — (1)1.6 (1)1.6 (1)1.6 (2)0.7(2)0.7 (2)0.7 (3)0.8 (3)0.8 (3)0.8 (4)1.0 (4)1.0 (4)1.0 total content(g) 0 4.1 4.1 4.1 Hardener material amine base amine base amine baseamine base content (g) 4 4 4 4 Light-shielding dye content ratio (%)35.5 20.2 50.6 20.2 film for Thickness (μm) 5 5 5 5 optical element

TABLE 4 Light-shielding coating Light-shielding coating Light-shieldingcoating and film for optical and film for optical and film for opticalelement: M element: N element: O Light- Resin material epoxy epoxy epoxyshielding content (g) 4 4 4 coating Dye material (1)-(3)azo dye(1)-(3)azo dye (1)-(3)azo dye for (4)phthalocyanine dye(4)phthalocyanine dye (4)phthalocyanine dye optical model No. (1)dyeblack (1)dye black (1)dye black element (2)dye red (2)dye red (2)dye red(3)dye yellow (3)dye yellow (3)dye yellow (4)dye blue (4)dye blue (4)dyeblue content (g) (1)0.55 (1)0.55 (1)0.55 (2)1.36 (2)1.36 (2)1.36 (3)0.55(3)0.55 (3)0.55 (4)2.17 (4)2.17 (4)2.17 total dye content (g) 4.63 4.634.63 Black material — — — pigment particle diameter (μm): — — — afteraggregation content (g) 0 0 0 Non-black material titania (dispersed intitania (dispersed in titania (dispersed in particle propylene glycolpropylene glycol propylene glycol monomethyl ether, solid monomethylether, solid monomethyl ether, solid content: 25 wt %) content: 25 wt %)content: 25 wt %) particle diameter (nm) 20 20 20 content (g): solid 5 55 content weight Solvent material propylene glycol propylene glycolpropylene glycol monomethyl ether monomethyl ether monomethyl ethercontent (g) 12 12 12 Coupling material epoxy-based silane epoxy-basedsilane epoxy-based silane agent coupling agent coupling agent couplingagent content (g) 1.2 1.2 1.2 Surface- material (1)nano-silica(1)nano-silica (1)nano-silica reflection (hydrophilic) (hydrophilic)(hydrophilic) inhibitor (2)nano-silica (2)nano-silica (2)nano-silica(hydrophobic) (hydrophobic) (hydrophobic) (3)sericite (3)sericite(3)sericite (4)quartz (4)quartz (4)quartz content (g) (1)1.6 (1)1.6(1)1.6 (2)0.7 (2)0.7 (2)0.7 (3)0.8 (3)0.8 (3)0.8 (4)1.0 (4)1.0 (4)1.0total content (g) 4.1 4.1 4.1 Hardener material amine base amine baseamine base content (g) 4 4 4 Light- dye content ratio (%) 20.2 20.2 20.2shielding Thickness (μm) 2 10 50 film for optical element

TABLE 5 Light-shielding Light-shielding Light-shielding Light-shieldingcoating and coating and coating and coating and film for optical filmfor optical film for optical film for optical element: R element: Selement: T element: U Light-Shielding Resin material epoxy epoxy epoxyepoxy coating for content (g) 4 4 4 4 optical element Inorganic blackmaterial carbon black- carbon black- titanium black- titanium black-particle with coated titania coated zirconia coated titania coatedzirconia a d-line d-line refractive index 2.5 2.2 2.5 2.2 refractiveparticle diameter (nm) 20 20 20 20 index of content (g): solid 1.5 10.91.5 1.5 2.2 to 3.5 content weight Solvent material propylene glycolpropylene glycol propylene glycol propylene glycol monomethyl ethermonomethyl ether monomethyl ether monomethyl ether content (g) 24 24 2424 Coupling material epoxy-based epoxy-based epoxy-based epoxy-basedagent silane coupling silane coupling silane coupling silane couplingagent agent agent agent content (g) 1.2 1.2 1.2 1.2 Surface- material(1)nano-silica (1)nano-silica (1)nano-silica (1)nano-silica reflection(hydrophilic) (hydrophilic) (hydrophilic) (hydrophilic) inhibitor(2)nano-silica (2)nano-silica (2)nano-silica (2)nano-silica(hydrophobic) (hydrophobic) (hydrophobic) (hydrophobic) (3)sericite(3)sericite (3)sericite (3)sericite (4)quartz (4)quartz (4)quartz(4)quartz content (g) (1)1.6 (1)1.6 (1)1.6 (1)1.6 (2)0.7 (2)0.7 (2)0.7(2)0.7 (3)0.8 (3)0.8 (3)0.8 (3)0.8 (4)1.0 (4)1.0 (4)1.0 (4)1.0 totalcontent (g) 4.1 4.1 4.1 4.1 Hardener material amine base amine baseamine base amine base content (g) 4 4 4 4 Light-shielding Content (%) ofinorganic black 10 45 10 10 film for particle with a d-line opticalelement refractive index of 2.2 to 3.5 Thickness (μm) 5 5 5 5

TABLE 6 Light-shielding Light-shielding Light-shielding Light-shieldingcoating and coating and coating and coating and film for optical filmfor optical film for optical film for optical element: V element: Welement: X element: Y Light-shielding Resin material epoxy epoxy epoxyepoxy coating for content (g) 4 4 4 4 optical element Inorganic blackmaterial TiN TiN TiN TiN particle with d-line refractive index 3.5 3.53.5 3.5 a d-line particle diameter (nm) 20 100 20 20 refractive content(g): solid 1.8 1.8 11 1.8 index of content weight 2.2 to 3. 5 Solventmaterial propylene glycol propylene glycol propylene glycol propyleneglycol monomethyl ether monomethyl ether monomethyl ether monomethylether content (g) 24 24 24 24 Coupling material epoxy-based epoxy-basedepoxy-based epoxy-based agent silane coupling silane coupling silanecoupling silane coupling agent agent agent agent content (g) 1.2 1.2 1.21.2 Surface- material (1)nano-silica (1)nano-silica (1)nano-silica(1)nano-silica reflection (hydrophilic) (hydrophilic) (hydrophilic)(hydrophilic) inhibitor (2)nano-silica (2)nano-silica (2)nano-silica(2)nano-silica (hydrophobic) (hydrophobic) (hydrophobic) (hydrophobic)(3)sericite (3)sericite (3)sericite (3)sericite (4)quartz (4)quartz(4)quartz (4)quartz content (g) (1)1.6 (1)1.6 (1)1.6 (1)1.6 (2)0.7(2)0.7 (2)0.7 (2)0.7 (3)0.8 (3)0.8 (3)0.8 (3)0.8 (4)1.0 (4)1.0 (4)1.0(4)1.5 total content (g) 4.1 4.1 4.1 4.1 Hardener material amine baseamine base amine base amine base content (g) 4 4 4 4 Light-shieldingContent (%) of inorganic black 12 12 45 12 film for particle with ad-line optical element refractive index of 2.2 to 3.5 Thickness (μm) 5 55 5

TABLE 7 Light-shielding coating and film for optical element: ADLight-shielding Resin material epoxy coating for content (g) 4 opticalDye material azo dye element model No. (1)dye black (2)dye red (3)dyeyellow (4)dye blue content (g) (1)0.202 (2)0.499 (3)0.202 (4)0.797 totaldye content (g) 1.7 Black pigment material — particle diameter (μm) —content (g) 0 Non-black particle material titania (dispersed inpropylene glycol monomethyl ether, solid content: 25 wt %) particlediameter (nm) 20 content (g): solid 2 content weight Solvent materialpropylene glycol monomethyl ether content (g) 24 Coupling agent materialepoxy-based silane coupling agent content (g) 1.9 Surface-reflectionmaterial — inhibitor content (g) — total content (g) 1.4 Hardenermaterial amine base content (g) 1.63 Light-shielding dye content (%)13.0 film for optical Thickness (μm) 5 element (Note 1) AppearanceExcellent: no problem in color tone, and no roughness Good: lens,itself, having a slightly deteriorated color tone that is not recognizedin the state that the lens is incorporated in a lens barrel or havingroughness that is not recognized in the state that the lens isincorporated in a lens barrel (Note 2) Performance in the stateincorporated in lens barrel Excellent: no occurrence of flare and ghostGood: no occurrence of flare and ghost, but there is a chance ofdefectiveness that the lens is not incorporated into a lens barrel Poor:occurrence of flare and ghost

Evaluation Results

Light-shielding coatings and films for optical element A, B, C, D, E, F,G, H, I, J, K, L, M, N, O, R, S, T, U, V, W, X, Y, and AD, theirinner-surface reflectance, degree of blackness, appearance, andperformance in the state incorporated in lens barrel were evaluated bythe above-described methods.

As the measurement results, the average extinction coefficient k was0.03 or more and 0.15 or less. It is desirable that the inner-surfacereflectance at an incident angle of 36.73° is 0.05% or less, theinner-surface reflectance at an incident angle of 45° is 0.07% or less,and the inner-surface reflectance at an incident angle of 68.13° is 1%or less. In addition, it is desirable that the degree of blackness is0.7 or more.

Each physical property of light-shielding coating and light-shieldingfilm for optical element A was measured and is shown as Example 1 inTable 8. The average extinction coefficient k was calculated byEquations (3), (4), and (5) as below. First, the average I (40.1%) ofthe measured values of transmittance for light having wavelengths from400 to 700 nm was substituted into Equation (3) to obtain an OD value of0.40. Then, the values, OD=0.40 and L=1 (μm), were substituted intoEquation (4) to obtain an α value of 0.91, and the resulting value,α=0.91, was substituted into Equation (5) to calculate an averageextinction coefficient k of 0.04. The inner-surface reflectance at anincident angle of 68.13° was 0.64%, the inner-surface reflectance at anincident angle of 45° was 0.0052%, and the inner-surface reflectance atan incident angle of 36.73° was 0.032%. Regarding the degree ofblackness, in the wavelength range from 400 to 700 nm, the minimumtransmittance was 41.8% at 687 nm, and the maximum transmittance was59.8% at 596 nm. These values were substituted into Equation (7) toobtain a degree of blackness of 0.7. The appearance was satisfactory inboth roughness and color tone. Furthermore, no flare and ghost wereobserved in evaluation of an image shot by the camera in which atelescopic lens provided with light-shielding film A was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm B, in which the dye content was about 50% unlike Example 1, isshown as Example 2 in Table 8. The average extinction coefficient k, theinner-surface reflectance at incident angles of 36.73°, 45°, and 68.13°,and the degree of blackness were all satisfactory. In addition, theappearance was satisfactory in both roughness and color tone.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film B was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm C, in which dye and carbon black (Mitsubishi carbon black MA100)having a diameter, after dispersion, of 0.1 μm were contained unlikeExample 1, is shown as Example 3 in Table 8. The average extinctioncoefficient k, the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13°, and the degree of blackness were allsatisfactory. In addition, regarding the appearance, though roughnesswas observed, color tone was satisfactory. Furthermore, no flare andghost were observed in evaluation of an image shot by the camera inwhich a telescopic lens provided with light-shielding film C wasincorporated.

Each physical property of light-shielding coating and light-shieldingfilm D, in which dye and carbon black (Mitsubishi carbon black MA100)having a diameter, after dispersion, of 10 μm were contained unlikeExample 1, is shown as Example 4 in Table 8. The average extinctioncoefficient k, the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13°, and the degree of blackness were allsatisfactory. In addition, regarding the appearance, though roughnesswas observed, color tone was satisfactory. Furthermore, no flare andghost were observed in evaluation of an image shot by the camera inwhich a telescopic lens provided with light-shielding film D wasincorporated.

Each physical property of light-shielding coating and light-shieldingfilm E, in which dye and copper-manganese complex oxide (BLACK PIGMENTSLURRY: C. I. Kasei) serving as pigment were contained unlike Example 1,is shown as Example 5 in Table 9. The average extinction coefficient k,the inner-surface reflectance at incident angles of 36.73°, 45°, and68.13°, and the degree of blackness were all satisfactory. In addition,regarding the appearance, though roughness was observed, color tone wassatisfactory. Furthermore, no flare and ghost were observed inevaluation of an image shot by the camera in which a telescopic lensprovided with light-shielding film E was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm F, in which dye and titanium black (13M: Mitsubishi Materials)serving as pigment were contained unlike Example 1, is shown as Example6 in Table 9. The average extinction coefficient k, the inner-surfacereflectance at incident angles of 36.73°, 45°, and 68.13°, and thedegree of blackness were all satisfactory. In addition, regarding theappearance, though roughness was observed, color tone was satisfactory.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film F was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm G, in which dye and copper oxide (Nisshin Engineering) serving aspigment were contained unlike Example 1, is shown as Example 7 in Table9. The average extinction coefficient k, the inner-surface reflectanceat incident angles of 36.73°, 45°, and 68.13°, and the degree ofblackness were all satisfactory. In addition, regarding the appearance,though roughness was observed, color tone was satisfactory. Furthermore,no flare and ghost were observed in evaluation of an image shot by thecamera in which a telescopic lens provided with light-shielding film Gwas incorporated.

Each physical property of light-shielding coating and light-shieldingfilm H, in which the dye content was about 60% unlike Example 1, isshown as Example 8 in Table 9. The average extinction coefficient k, theinner-surface reflectance at incident angles of 36.73°, 45°, and 68.13°,and the degree of blackness were all satisfactory. In addition, theappearance was satisfactory in both roughness and color tone.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film H was incorporated. However, durability oflight-shielding film A was superior to that of light-shielding film H.

Each physical property of light-shielding coating and light-shieldingfilm I, in which dye and iron oxide (Fe₂O₃: Sakai Chemical Industry)serving as pigment were contained unlike Example 1, is shown as Example9 in Table 10. Iron oxide is reddish, therefore, the average extinctioncoefficient k and the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13° were satisfactory, but the degree of blacknesswas low, i.e., 0.6. Regarding the appearance, though roughness wasobserved, color tone was satisfactory. Furthermore, no flare and ghostwere observed in evaluation of an image shot by the camera in which atelescopic lens provided with light-shielding film I was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm J, in which the dye content was 20 wt %, the amount of thenon-black particles was increased to 5 g, and a blue dye and asurface-reflection inhibitor were contained, is shown as Example 10 inTable 9. As the materials of the surface-reflection inhibitor, thefollowings were used: silica (hydrophilic) was hydrophilic Aerozilhaving an average particle diameter of about 10 nm (any of Aerozil 90,150, 200, 300, and 380: Nippon Aerozil); silica (hydrophobic) washydrophobic Aerozil having an average particle diameter of about 10 nm(any of Aerozil R972, R974, R104, R106, R202, R805, and R812: NipponAerozil); quartz was Crystallite having an average particle diameter ofabout 10 μm (any of A-1, A-A, VX-S2, VX-S, and 5X: Tatsumori); andsericite was Takara Mica M-101 (manufactured by Shiraishi Calcium Co.,Ltd.) or Hikawa Mica Z20 (manufactured by Hikawa Kogyo Co., Ltd.) havingan average particle diameter of about 10 μm. The blue dye used was anyof the followings: VALIFAST BLUE 1605 (Orient Chemical), VALIFAST BLUE2650 (Orient Chemical), VALIFAST BLUE 2620 (Orient Chemical), VALIFASTBLUE 2606 (Orient Chemical), and Aizen Victoria Pure Blue BOH (HodogayaChemical). As a result, the average extinction coefficient k was 0.03.Furthermore, the inner-surface reflectance at an incident angle of36.73° was very good. In addition, the inner-surface reflectance at anincident angle of 68.13° was satisfactory. The appearance wassatisfactory in both roughness and color tone. Furthermore, no flare andghost were observed in evaluation of an image shot by the camera inwhich a telescopic lens provided with light-shielding film J wasincorporated.

Each physical property of light-shielding coating and light-shieldingfilm K, in which a surface-reflection inhibitor and a blue dye werecontained and the dye content was about 50 wt % unlike Example 1, isshown as Example 11 in Table 10. The average extinction coefficient k,the inner-surface reflectance at incident angles of 36.73°, 45°, and68.13°, and the degree of blackness were all satisfactory. In addition,the appearance was satisfactory in both roughness and color tone.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film K was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm L, in which a surface-reflection inhibitor and a blue dye werecontained, and zirconia (Sumitomo Osaka Cement) was used as non-blackparticles unlike Example 1, is shown as Example 12 in Table 10. Theaverage extinction coefficient k, the inner-surface reflectance atincident angles of 36.73°, 45°, and 68.13°, and the degree of blacknesswere all satisfactory. In addition, the appearance was satisfactory inboth roughness and color tone. Furthermore, no flare and ghost wereobserved in evaluation of an image shot by the camera in which atelescopic lens provided with light-shielding film L was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm M, in which a surface-reflection inhibitor and a blue dye werecontained, and the thickness was adjusted to 2 μm unlike Example 1, isshown as Example 13 in Table 11. The average extinction coefficient k,the inner-surface reflectance at incident angles of 36.73°, 45°, and68.13°, and the degree of blackness were all satisfactory. In addition,the appearance was satisfactory in both roughness and color tone.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film M was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm N, in which a surface-reflection inhibitor and a blue dye werecontained, and the thickness was adjusted to 10 μm unlike Example 1, isshown as Example 14 in Table 11. The average extinction coefficient k,the inner-surface reflectance at incident angles of 36.73°, 45°, and68.13°, and the degree of blackness were all satisfactory. In addition,the appearance was satisfactory in both roughness and color tone.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film N was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm O, in which a surface-reflection inhibitor and a blue dye werecontained, and the thickness was adjusted to 50 μm unlike Example 1, isshown as Example 15 in Table 11. The average extinction coefficient k,the inner-surface reflectance at incident angles of 36.73°, 45°, and68.13°, and the degree of blackness were all satisfactory. In addition,the appearance was satisfactory in both roughness and color tone.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film O was incorporated. However, defective lenses thatwere not smoothly incorporated into lens barrels occurred.

Each physical property of light-shielding coating and light-shieldingfilm R, in which 10 wt % of carbon black-coated titania having aparticle diameter of 20 nm was contained in the colorant unlike Example1, is shown as Example 16 in Table 11.

The average extinction coefficient k, the inner-surface reflectance atincident angles of 36.73°, 45°, and 68.13°, and the degree of blacknesswere all satisfactory. In addition, regarding the appearance, thoughroughness was observed, color tone was satisfactory. Furthermore, noflare and ghost were observed in evaluation of an image shot by thecamera in which a telescopic lens provided with light-shielding film Rwas incorporated.

Each physical property of light-shielding coating and light-shieldingfilm S, in which 45 wt % of carbon black-coated zirconia having aparticle diameter of 20 nm was contained in the colorant unlike Example16, is shown as Example 17 in Table 12. The average extinctioncoefficient k, the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13°, and the degree of blackness were allsatisfactory. In addition, regarding the appearance, though roughnesswas observed, color tone was satisfactory. Furthermore, no flare andghost were observed in evaluation of an image shot by the camera inwhich a telescopic lens provided with light-shielding film S wasincorporated.

Each physical property of light-shielding coating and light-shieldingfilm T, in which 10 wt % of titanium black-coated titania having aparticle diameter of 20 nm was contained in the colorant unlike Example16, is shown as Example 18 in Table 12. The average extinctioncoefficient k, the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13°, and the degree of blackness were allsatisfactory. In addition, regarding the appearance, though roughnesswas observed, color tone was satisfactory. Furthermore, no flare andghost were observed in evaluation of an image shot by the camera inwhich a telescopic lens provided with light-shielding film T wasincorporated.

Each physical property of light-shielding coating and light-shieldingfilm U, in which 10 wt % of carbon black-coated zirconia having aparticle diameter of 20 nm was contained in the colorant unlike Example16, is shown as Example 19 in Table 12. The average extinctioncoefficient k, the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13°, and the degree of blackness were allsatisfactory. In addition, regarding the appearance, though roughnesswas observed, color tone was satisfactory. Furthermore, no flare andghost were observed in evaluation of an image shot by the camera inwhich a telescopic lens provided with light-shielding film U wasincorporated.

Each physical property of light-shielding coating and light-shieldingfilm V, in which 12 wt % of TiN having a particle diameter of 20 nm wascontained in the colorant unlike Example 16, is shown as Example 20 inTable 13. The average extinction coefficient k, the inner-surfacereflectance at incident angles of 36.73°, 45°, and 68.13°, and thedegree of blackness were all satisfactory. In addition, regarding theappearance, though roughness was observed, color tone was satisfactory.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film V was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm W, in which 12 wt % of TiN having a particle diameter of 100 nm wascontained in the colorant unlike Example 20, is shown as Example 21 inTable 13. The average extinction coefficient k, the inner-surfacereflectance at incident angles of 36.73°, 45°, and 68.13°, and thedegree of blackness were all satisfactory. In addition, regarding theappearance, though roughness was observed, color tone was satisfactory.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film W was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm X, in which 45 wt % of TiN having a particle diameter of 20 nm wascontained in the colorant unlike Example 20, is shown as Example 22 inTable 13. The average extinction coefficient k, the inner-surfacereflectance at incident angles of 36.73°, 45°, and 68.13°, and thedegree of blackness were all satisfactory. In addition, regarding theappearance, though roughness was observed, color tone was satisfactory.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film X was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm Y, in which 12 wt % of TiN having a particle diameter of 110 nm wascontained in the colorant unlike Example 17, is shown as Example 23 inTable 13. The average extinction coefficient k, the inner-surfacereflectance at incident angles of 36.73°, 45°, and 68.13°, and thedegree of blackness were all satisfactory. In addition, regarding theappearance, though roughness was observed, color tone was satisfactory.Furthermore, no flare and ghost were observed in evaluation of an imageshot by the camera in which a telescopic lens provided withlight-shielding film Y was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm AD, in which 13 wt % of a dye was contained in the colorant unlikeExample 1, is shown as Example 24 in Table 14. The average extinctioncoefficient k, the inner-surface reflectance at incident angles of36.73°, 45°, and 68.13°, and the degree of blackness were allsatisfactory. Furthermore, no flare and ghost were observed inevaluation of an image shot by the camera in which a telescopic lensprovided with light-shielding film Y was incorporated.

TABLE 8 Example 1 Example 2 Example 3 Example 4 Evaluation Extinctioncoefficient 0.04 0.05 0.15 0.1 of optical inner-surface incident angleafter 0.64 0.62 0.67 0.65 properties reflectance(Ave. refraction: 68.13°400-700 nm %) incident angle after 0.052 0.041 0.064 0.029 refraction:45° incident angle after 0.032 0.026 0.048 0.029 refraction: 36.73°Degree of blackness 0.70 0.70 0.90 0.90 Appearance excellent excellentgood good Performance at fitting in lens barrel excellent excellentexcellent excellent

TABLE 9 Example 5 Example 6 Example 7 Example 8 Evaluation Extinctioncoefficient 0.09 0.05 0.04 0.06 of optical inner-surface incident angleafter 0.59 0.62 0.62 0.62 properties reflectance(Ave. refraction: 68.13°400-700 nm %) incident angle after 0.021 0.032 0.040 0.041 refraction:45° incident angle after 0.014 0.020 0.024 0.026 refraction: 36.73°Degree of blackness 0.90 0.80 0.80 0.70 Appearance good good goodexcellent Performance at fitting in lens barrel excellent excellentexcellent excellent

TABLE 10 Example 9 Example 10 Example 11 Example 12 EvaluationExtinction coefficient 0.11 0.03 0.05 0.03 of optical inner-surfaceincident angle after 0.66 0.26 0.27 0.9 properties reflectance(Ave.refraction: 68.13° 400-700 nm %) incident angle after 0.035 0.003 ≦0.0010.003 refraction: 45° incident angle after 0.033 0.002 ≦0.001 0.002refraction: 36.73° Degree of blackness 0.60 0.8 0.8 0.7 Appearance goodexcellent excellent excellent Performance at fitting in lens barrelexcellent excellent excellent excellent

TABLE 11 Example 13 Example 14 Example 15 Evaluation Extinctioncoefficient 0.03 0.03 0.03 of optical inner-surface incident angle after0.26 0.25 0.25 properties reflectance (Ave. refraction: 68.13° 400-700nm %) incident angle after 0.04 ≦0.001 ≦0.001 refraction: 45° incidentangle after 0.03 ≦0.001 ≦0.001 refraction: 36.73° Degree of blackness0.7 0.7 0.7 Appearance excellent excellent excellent Performance atfitting in lens barrel excellent excellent good

TABLE 12 Example 16 Example 17 Example 18 Example 19 EvaluationExtinction coefficient 0.03 0.15 0.03 0.03 of optical inner-surfaceincident angle after 0.29 0.88 0.31 0.92 properties reflectance (Ave.refraction: 68.13° 400-700 nm %) incident angle after 0.03 0.04 0.030.03 refraction: 45° incident angle after 0.02 0.03 0.02 0.02refraction: 36.73° Degree of blackness 1 1 1 1 Appearance good good goodgood Performance at fitting in lens barrel excellent excellent excellentexcellent

TABLE 13 Example 20 Example 21 Example 22 Example 23 EvaluationExtinction coefficient 0.03 0.03 0.15 0.03 of optical inner-surfaceincident angle after 0.18 0.21 0.11 0.2 properties reflectance (Ave.refraction: 68.13° 400-700 nm %) incident angle after 0.03 0.04 0.040.07 refraction: 45° incident angle after 0.02 0.03 0.03 0.05refraction: 36.73° Degree of blackness 1 1 1 1 Appearance good good goodgood Performance at fitting in lens barrel excellent excellent excellentexcellent

TABLE 14 Example 24 Extinction coefficient 0.03 inner-surface incidentangle after refraction: 0.42 reflectance (Ave. 68.13° 400-700 nm %)incident angle after refraction: 45° 0.06 incident angle afterrefraction: 0.04 36.73° Degree of blackness 0.8 Appearance goodPerformance at fitting in lens barrel excellent

Comparative Examples 1 to 6

In Comparative Examples, preparation of light-shielding coatings foroptical element, production of light-shielding films for opticalelement, and evaluation of optical properties were performed as in theabove-described Examples 1 to 23, except the followings.

Tables 15 and 16 show resins, dyes, black pigments, non-black particles,solvents, coupling agents, and their mixing ratios constitutinglight-shielding coatings and films for optical element P, Q, Z, AA, AB,and AC.

Tables 17 and 18 show the results of optical property evaluation oflight-shielding coatings and films for optical element P, Q, Z, AA, AB,and AC as Comparative Examples 1, 2, 3, 4, 5, and 6, respectively.

TABLE 15 Light-shielding coating Light-shielding coating and film foroptical and film for optical element: P element: Q Light- Resin materialepoxy epoxy shielding content (g) 4 4 coating for Dye material azo dyeazo dye optical model No. (1)dye black (1)dye black element (2)dye red(2)dye red (3)dye yellow (3)dye yellow (4)dye blue (4)dye blue content(g) (1)0.148 (1)4 (2)0.367 (2)2.9 (3)0.148 (3)0.375 (4)0.586 total dye1.5 7.275 content (g) Black material — carbon black pigment particle —0.1 diameter (μm): after aggregation content (g) 0 3 Non-black materialtitania (dispersed in titania (dispersed in particle propylene glycolpropylene glycol monomethyl ether, solid monomethyl ether, solidcontent: 25 wt %) content: 25 wt %) particle 20 20 diameter (nm) content(g): 2 2 solid content weight Solvent material propylene glycolpropylene glycol monomethyl ether monomethyl ether content (g) 24 24Coupling material epoxy-based silane epoxy-based silane agent couplingagent coupling agent content (g) 1.9 1.2 Surface- material — —reflection content (g) — — inhibitor total content (g) 1.4 0 Hardenermaterial amine base amine base content (g) 1.63 4 Light- dye content12.0 33.9 shielding film ratio (%) for optical Thickness (μm) 5 5element

TABLE 16 Light-shielding Light-shielding Light-shielding Light-shieldingcoating and coating and coating and coating and film for optical filmfor optical film for optical film for optical element: Z element: AAelement: AB element: AC Light-shielding Resin material epoxy epoxy epoxyepoxy coating for content (g) 4 4 4 4 optical element Inorganic blackmaterial TiN TiN TiN TiN particle with d-line refractive index 3.5 3.53.5 3.5 a d-line particle diameter (nm) 20 20 20 20 refractive content(g): solid 1.2 1.2 1.5 5 index of content weight 2.2 to 3.5 Solventmaterial propylene glycol propylene glycol propylene glycol propyleneglycol monomethyl ether monomethyl ether monomethyl ether monomethylether content (g) 24 24 24 24 Coupling material epoxy-based epoxy-basedepoxy-based epoxy-based agent silane coupling silane coupling silanecoupling silane coupling agent agent agent agent content (g) 1.2 1.2 1.21.2 Surface- material (1)nano-silica (1)nano-silica (1)nano-silica(1)nano-silica reflection (hydrophilic) (hydrophilic) (hydrophilic)(hydrophilic) inhibitor (2)nano-silica (2)nano-silica (2)nano-silica(2)nano-silica (hydrophobic) (hydrophobic) (hydrophobic) (hydrophobic)(3)sericite (3)sericite (3)sericite (3)sericite (4)quartz (4)quartz(4)quartz (4)quartz content (g) (1)1.6 (1)1.6 (1)1.6 (1)1.6 (2)0.7(2)0.7 (2)0.7 (2)0.7 (3)0.8 (3)0.8 (3)0.8 (3)0.8 (4)1.1 (4)1.2 (4)1.3(4)1.4 total content (g) 4.1 4.1 4.1 4.1 Hardener material amine baseamine base amine base amine base content (g) 4 4 4 4 Light-shieldingContent (%) of inorganic black 8 47 10 27 film for particle with ad-line optical element refractive index of 2.2 to 3.5 Thickness (μm) 5 55 5

In Comparative Example 1, light-shielding coating and film for opticalelement P, in which the dye content was decreased compared with that inExample 1, was used. As a result, in the light-shielding film foroptical element of Comparative Example 1, the extinction coefficient waslow, i.e., 0.02, and the inner-surface reflectance at incident angles of45° and 36.73° was inferior. However, the deterioration of theinner-surface reflection at an incident angle of 68.13°, which is largerthan the total reflection angle, was small. Flare and ghost werevisually observed in evaluation of an image shot by the camera in whicha lens provided with light-shielding film P was incorporated.

In Comparative Example 2, light-shielding coating and film for opticalelement Q, in which the dye content and the carbon content wereincreased compared with those in Example 3, was used. As a result, inthe light-shielding film for optical element of Comparative Example 2,the extinction coefficient was high, i.e., 0.17, and the inner-surfacereflectance at incident angles of 45° and 36.73° was inferior. Regardingthe appearance, though roughness was observed, color tone wassatisfactory. Flare and ghost were visually observed in evaluation of animage shot by the camera in which a lens provided with light-shieldingfilm Q was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm Z, in which 8 wt % of carbon black-coated zirconia having aparticle diameter of 20 nm was contained in the colorant unlike Example17, is shown as Comparative Example 3 in Table 16. As a result, in thelight-shielding film for optical element of Comparative Example 3, theextinction coefficient was low, i.e., 0.02, and the inner-surfacereflectance at incident angles of 45° and 36.73° was inferior. Regardingthe appearance, though roughness was observed, color tone wassatisfactory. Flare and ghost were visually observed in evaluation of animage shot by the camera in which a lens provided with light-shieldingfilm Z was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm AA, in which 47 wt % of carbon black-coated zirconia having aparticle diameter of 20 nm was contained in the colorant unlike Example17, is shown as Comparative Example 4 in Table 16. As a result, in thelight-shielding film for optical element of Comparative Example 4, theextinction coefficient was high, i.e., 0.17, and the inner-surfacereflectance at incident angles of 45° and 36.73° was inferior. Regardingthe appearance, though roughness was observed, color tone wassatisfactory. Flare and ghost were visually observed in evaluation of animage shot by the camera in which a lens provided with light-shieldingfilm AA was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm AB, in which 10 wt % of TiN having a particle diameter of 20 nm wascontained in the colorant unlike Example 20, is shown as ComparativeExample 5 in Table 16. As a result, in the light-shielding film foroptical element of Comparative Example 5, the extinction coefficient waslow, i.e., 0.02, and the inner-surface reflectance at incident angles of45° and 36.73° was inferior. Regarding the appearance, though roughnesswas observed, color tone was satisfactory. Flare and ghost were visuallyobserved in evaluation of an image shot by the camera in which a lensprovided with light-shielding film AB was incorporated.

Each physical property of light-shielding coating and light-shieldingfilm AC, in which 27 wt % of TiN having a particle diameter of 20 nm wascontained in the colorant unlike Example 16, is shown as ComparativeExample 6 in Table 16. As a result, in the light-shielding film foroptical element of Comparative Example 6, the extinction coefficient washigh, i.e., 0.17, and the inner-surface reflectance at incident anglesof 45° and 36.73° was inferior. Regarding the appearance, thoughroughness was observed, color tone was satisfactory. Flare and ghostwere visually observed in evaluation of an image shot by the camera inwhich a lens provided with light-shielding film AC was incorporated.

TABLE 17 Comparative Comparative Example 1 Example 2 EvaluationExtinction coefficient 0.02 0.17 of optical inner- incident angle after0.46 0.69 properties surface refraction: 68.13° reflectance incidentangle after 0.07 0.08 (Ave. refraction: 45° 400-700 incident angle after0.05 0.06 nm %) refraction: 36.73° Degree of blackness 0.8 0.9Appearance excellent good Performance at fitting in poor poor lensbarrel

TABLE 18 Comparative Comparative Comparative Comparative Example 3Example 4 Example 5 Example 6 Evaluation Extinction coefficient 0.020.17 0.02 0.17 of optical inner-surface incident angle after 0.98 0.850.17 0.1 properties reflectance (Ave. refraction: 68.13° 400-700 nm %)incident angle after 0.08 0.08 0.08 0.08 refraction: 45° incident angleafter 0.07 0.07 0.07 0.07 refraction: 36.73° Degree of blackness 1 1 1 1Appearance good good good good Performance at fitting in lens barrelpoor poor poor poor

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2010-029514 filed Feb. 12, 2010 and No. 2011-002163 filed Jan. 7, 2011,which are hereby incorporated by reference herein in their entirety.

1. A light-shielding film for optical element comprising: a resin; and acolorant, wherein the average of extinction coefficient of the wholelight-shielding film for light having wavelengths ranging from 400 to700 nm is 0.03 or more and 0.15 or less.
 2. The light-shielding film foroptical element according to claim 1, wherein the colorant contains 20wt % or more and 50 wt % or less of dye.
 3. The light-shielding film foroptical element according to claim 1, wherein the colorant contains dyeand pigment; and the pigment is composed of at least one selected fromthe group consisting of carbon black, copper-manganese complex oxide,titanium black, and copper oxide, each having an average particlediameter of 0.1 μm or more and 10 μm or less.
 4. The light-shieldingfilm for optical element according to claim 1, further comprising:non-black particles having an average particle diameter of 100 nm orless and a refractive index (nd) of 2.2 or more.
 5. The light-shieldingfilm for optical element according to claim 4, wherein the non-blackparticles are titania, zirconia, or a mixture thereof.
 6. Thelight-shielding film for optical element according to claim 1, whereinthe colorant is composed of inorganic black particles having a d-linerefractive index of 2.2 or more and 3.5 or less.
 7. The light-shieldingfilm for optical element according to claim 6, wherein the inorganicblack particles are TiN, titania covered with carbon black, titaniacovered with titanium black, zirconia covered with carbon black, orzirconia covered with titanium black, each having an average particlediameter of 100 nm or less.
 8. The light-shielding film for opticalelement according to claim 1, wherein the light-shielding film foroptical element has an average thickness of 2 μm or more and 30 μm orless; and the ratio of a minimum transmittance to a maximumtransmittance, (minimum transmittance)/(maximum transmittance), of thelight-shielding film for light having wavelengths ranging from 400 to700 nm is 0.7 or more.
 9. The light-shielding film for optical elementaccording to claim 1, wherein the light-shielding film has a differencein extinction coefficient thereof and is applied to an optical elementin such a manner that the side having a smaller extinction coefficientthan the average extinction coefficient of the whole light-shieldingfilm is brought into the contact with the optical element.
 10. Anoptical element having an outer portion on which the light-shieldingfilm for optical element according to claim 1 is provided.